Keyboard with reed contacts



- Oct. 6, 1970 T STE|NBACH EI'AL KEYBOARD WITH REED CONTACTS Filed Aug. l6, 1967 T 4 Sheets-Sheet 1 3 g No No 1- A 0 o (a) Fig.7

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mvsmons ATTORNEY Oct. 6, 1970 H. STEINBACH ET AL 3,533,029

KEYBOARD WITH REED CONTACTS Filed Aug. 16, 1967 4 SheetsSheet 2 Fig.4

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United States Patent 3,533,029 KEYBOARD WITH REED CONTACTS Heinz Steinbach, Kornwestheim, Andreas Zerfass, Stuttgart-Stammheim, and Gerhard Wessel, Kornwestheim, Germany, assignors to International Standard Electric Corporation, New York, N.Y., a corporation of Delaware Filed Aug. 16, 1967, Ser. No. 660,964 Claims priority, application Germany, Aug. 24, 1966, St 25,800 Int. Cl. H01h 51/78 US. Cl. 335-206 6 Claims ABSTRACT OF THE DISCLOSURE Reed contacts in a keyboard or key panel are actuated by axially polarized, mobile permanent magnets. The polarization, arrangement and shape of the magnets are selected so that extraneous magnetic fields of adjacent magnets oppose each other and cancel to prevent undesired influences on their respective reed contacts.

The invention relates to a circuit arrangement, or keyboard, with reed contacts which are actuated by movable axially polarized permanent magnets. It relates particularly to key-dialling facilities in telecommunication systems or other information-processing systems.

In a keyboard according to the invention reed contacts are used with two rod-shaped contacts melted into both ends of a reed tube, between which contacts a ball-shaped armature is freely movable.

It is generally knOWn to use reed contacts in key-controlled switching facilities. In an arrangement of this type, known to the art, a permanent magnet is fastened to a leaf-type spring arranged perpendicular to the reed contact, as a key knob. When the leaf-type spring is pressed down, the permanent magnet approaches the associated reed contact whereby said reed contact is actuated.

Moreover, an arrangement, comprising a plurality of keys is known in which at the key bodies, arranged like a matrix, one or several permanent magnets are provided, preferably arranged at an angle of 90 towards each other. When actuating one of the keys, the associated permanent magnets are shifted in the longitudinal direction thereby actuating those reed contacts which are closest to the key body.

Furthermore, a switching facility is known, having several keys and permanent magnet-actuated reed contacts in which in the recesses of flux guiding pieces of the magnetic circuit permanent magnets are fixed to the keys. The keys are movable and are plunged into the recesses or apertures when they are present. The permanent magnets are magnetized so that the magnetic field of a mobile permanent magnet opposes the magnetic field of a fixed permanent magnet and applied to the flux pieces, so that a previously actuated feed contact opens and closes again when the mobile permanent magnet is removed.

By using reed contacts, such key-controlled switching facilities show the advantage that they can also be used in explosion-endangered systems. If in such switching facilities or key panels the reed contacts are actuated by mobile permanent magnets, poled in the same direction, it occurs that the extraneous fields of the adjacent magnets interfere with the switching function of the reed contacts.

It is, therefore, an object of the invention to avoid. this disadvantage of known switching facilities and to eliminate the interference of extraneous fields of the permanent magnets onto adjacent reed contacts in a key panel with such contacts, actuated by mobile, axially polarized permanent magnets. This is achieved, according to the in-' vention, by polarization and by arranging and shaping the permanent magnets so that the permanent magnets of those reed contacts which can be reached by magnetic extraneous fields of adjacent permanent magnets, emit magnetic fields of such polarization, direction and intensity that the extraneous fields compensate each other.

According to a preferred embodiment of the invention, the permanent magnets are alternately poled in the opposite direction within the rows and/0r within the columns.

In a further embodiment of the invention a permanent magnet is associated with two or more reed contacts and the square-shaped permanent magnets have slotted holes for the reed contacts. The short edges of the squareshaped permanent magnets are preferably rounded.

The permanent magnets can also be formed, according to a further feature of the invention, as oval-shaped magnets or may accommodate the reed contacts in lateral recesses.

According to a further embodiment of the invention, the permanent magnets are turned around the key aXis at an angle of approximately 45 towards the position of the rows or columns respectively.

A switching facility or keyboard constructed in accordance with invention possesses various advantages. By polarizing, arranging and shaping the permanent magnets according to the invention, the functions of reed contacts are secured even with very close spacing of the individual elements without subjecting the reed contacts to interfering extraneous fields of adjacent permanent magnets.

The invention is described with the aid of the accompanying drawings, wherein:

FIG. 1 shows a key panel according to the invention in which the axially polarized permanent magnets within the columns are alternately poled in the opposite direction, seen from top and partly in section;

FIG. 2 shows the key panel according to FIG. I, seen from the side;

FIGS. 3 to 9 show further key panels according to the invention with different polarization, arrangement and shape of the permanent magnets, seen from the top.

In FIG. 1 flat, square-shaped permanent magnets are designated with 1, each having two slotted holes 2 and 3 for the reed contacts 4. The permanent magnets 1 are axially polarized i.e. in the direction of the key movement or the keyshaft 5 respectively and in the longitudinal direction of the reed contacts 4. Since the holes 2 and 3 of the permanent magnets 1 are slotted holes it is secured that, when using reed contacts 4 with ball-type armatures no preferably magnetized support can occur at one of the contacting elements melted into the reed tube. In the arrangement of FIG. 1 the permanent magnets 1 are poled alternately in the opposite direction within the columns (vertical). This construction shows a substantial improvement compared to the arrangements of key panels known having permanent magnets which are poled in the same direction, because the interfering extraneous fields of the permanent magnets 1 partly compensate each other.

FIG. 2 shows the key panel in a side View. As shown here, contacts 4 are operated by each permanent magnet 1. The permanent magnets 1 are fastened to the key shafts 5 and are moved in the direction of the arrows 7 against the resetting force of springs 6.

FIG. 3 shows a key panel in which the individual permanent magnets 1 are turned around the axis of the key at an angle of approximately 45 with respect to the arrange of the rows or columns. The short edges of the square-shaped permanent magnets 1 are rounded. The permanent magnets 1 are poled as shown in the arrangement according to FIG. 1, i.e. the permanent magnets 1 are poled alternately in the opposite direction within the columns (vertical). This construction results in a nearly complete compensation of the interfering extraneous fields of the permanent magnets FIGS. 4 and 6 show key panels in which the arrangement and shape of the permanent magnets 1 correspond to the ones shown in FIG. 1. However, the polarization is selected so that in FIG. 4 the permanent magnets 1 are alflernately poled in the opposite direction within the rows (horizontal) and in FIG. 6 they are poled in the opposite direction alternately within the rows as well as within the columns.

In the key panels shown on FIGS. and 7 the arrangement and the shape of the permanent magnets 1 correspond to the arrangement and shape shown in FIG. 3. The permanent magnets 1 of the key panel shown in FIG. 5, however, are alternately poled in the opposite direction within the rows while the permanent magnets 1 of the key panel shown in FIG. 7 are alternately poled in the opposite direction within the rows and within the columns.

The FIGS. 8 and 9 show further possible shapes of the permanent magnets 1 whereby the ones shown in FIG. 8 are oval-shaped and the permanent magnets shown in FIG. 9 accommodaate the reed contacts 4 in lateral recesses 8.

In all constructions the arrangement of the permanent magnets and the shape of the magnets are selected so that there is with reference to the reed contacts of a key approximately the same distance between the adjacent magnets, poled in the opposite direction.

While the principles of the invention have been described above in connection with specific apparatus and applications, it is to be understood that this description is made only by way of example and not as a limitation on the scope of the invention.

What is claimed is:

1. A switching device employing reed contacts actuated by axially polarized mobile permanent magnets for key-dialling facilities in telecommunication and other information-processing systems, wherein the improvement comprises:

a plurality of axially polarized permanent magnets providing magnetic fields,

said plurality of magnets including at least three magnets,

a slot in each permanent magnet,

a plurality of reed contacts, each of which is ar ranged to fit in one of said slots and to be activated by the magnetic field of the corresponding permanent magnet,

each permanent magnet being poled in a direction opposite to at least one adjacent permanent magnet to provide a component of its magnetic field to cancel interfering components of magnetic field from the adjacent permanent magnet.

2. A switching device according to claim 1 in which each permanent magnet is associated with two reed contacts and each magnet is square-shaped and has a hole prepared to receive each of the reed contacts.

3. A switching device according to claim 2 in which selected edges of the square-shaped permanent magnets are rounded.

4. A switching device according to claim 2 in which the permanent magnets are oval-shaped.

5. A switching device according to claim 2 in which the permanent magnets accommodate the reed contacts in lateral recesses.

6. A switching device according to claim 2 in which the reed contacts are arranged in rows and columns and the permanent magnets are turned about axes through their centers at substantially an angle of relative to the rows and columns.

References Cited UNITED STATES PATENTS 3,158,710 11/1964 Paglee. 3,273,088 9/1966 Grobe et al. 335-153 3,233,061 2/1966 Jones 335--205 X 3,283,274 11/1966 De Falco 335207 X BERNARD A. GILHEANY, Primary Examiner R. N. ENVALL, JR., Assistant Examiner US. Cl. X.R. 3 35-207 

